The present invention relates to a seat assembly having a seat cushion and a seat back with a latch mechanism. More specifically, the present invention relates to a seat latch mechanism which deforms, deflects, or compresses to absorb energy during a collision.
Many vehicles are provided with sophisticated seat assemblies that may be folded or collapsed when moved to a stowed position from a use or seat forming position. A large percentage of vehicles in present use have a folding seat back which pivots and folds onto the seat cushion to create a storage surface and allows access to the rear of the seat assembly. These folding and pivoting seat backs have further been adapted to include an integral seat belt such as a three point restraint. During a collision or rapid deceleration, a folding or forward tilting seat back having an integral seat belt will be subject to large inertial loads from both the mass of the occupant, transferred through the seat belt, and the mass of the seat back. The inertial load in many instances of such rapid deceleration will be significant and will place a large load onto a latch mechanism that fixes the seat back to the frame of the vehicle. Accordingly, there is a need in the art for a latch mechanism which can absorb the energy of a large inertial load and still maintain the structural integrity of a seat assembly.
It is an object of the present invention to attenuate the energy from a collision or rapid deceleration in a vehicle by employing an energy damping mechanism and an inertial lock for a seat back.
A further object of the present invention is to maintain the structural integrity for a seat assembly, during a collision or rapid deceleration, to generally maintain the upright position of a seat occupant in the seat assembly.
In accordance with the present invention, a vehicle seat assembly is provided with a latch mechanism for latching and unlatching the seat assembly in a use or seat forming position. The seat assembly in the preferred embodiment includes a pivotable seat back. A first pivoting mechanism supports the seat back and allows the seat back to be pivoted between a generally horizontal position folded upon a seat cushion and a generally vertical use position. The latch mechanism latches the seat back in response to the movement of the seat back from its stowed position to its seat forming position.
The latch mechanism of the present invention includes a sector support, a base plate or flange member attached to the vehicle floor, and a rotatable cam or catch for latching or releasing the seat back. The seat back in the preferred embodiment is coupled to the sector support which is further pivotably coupled to the base plate. The sector support includes an engagement surface which has been designed to mate with a stop on the base plate when a buckle zone on the base plate compresses or deflects under an external force. When an external force vector of sufficient magnitude is applied to the sector support (for example the force generated by a frontal collision), the buckle zone will compress or deflect to absorb the energy of the force. The deflection of the buckle zone will bring the engagement surface of the sector support into contact with the stop located on the base plate, and at the same time absorb the energy of the external force. The stop will prevent further motion of the seat back in a forward direction, maintaining an occupant on the seat assembly in a generally normal vertical position.
Furthermore, the engagement surface of the sector support has been configured with a profiled engagement surface. The profiled engagement surface has been shaped to guide and mate with the stop to create a snug or firm fit, stopping the movement of the sector support during the deflection of the buckle zone.